The present invention relates to the general field of electrocardiographs.
More particularly, the invention relates to an event-driven ambulatory electrocardiograph. Such a device makes it possible, advantageously, for a patient to record his or her own emergency electrocardiogram, e.g. at home, in the event of a supposed attack and without the presence or the assistance of any qualified medical personnel. It needs to be compact and simple to handle so that it can be positioned easily on the patient's chest in a position that is sufficiently stable to ensure good acquisition of signals, but without giving rise to additional stress for the patient.
Document EP 0 611 287 B1 describes a portable electrocardiograph enabling a twelve-lead electrocardiogram to be captured from the signals acquired by nine electrodes. A twelve-lead electrocardiogram enables various forms of cardiac or cardiovascular pathologies to be diagnosed such as arrhythmia or repolarization anomalies.
The signals representative of the patient's cardiac activity may be stored in the electrocardiograph in order to reproduce the electrocardiogram on a recording strip. They may also be converted into acoustic signals and transmitted by a loudspeaker over a telephone line to a remote center.
In the embodiment shown in FIG. 1A, the portable electrocardiograph 100 of document EP 0 611 287 B1 has a housing with a rigid support surface 114 with six precordial electrodes 101-106 placed thereon for application on the respective points V1-V6 of the patient's chest.
The support surface 114 is concave. In the meaning of the invention, a surface is “concave” or “substantially concave” when it is suitable for fitting around the curved chest of a patient, and is not necessarily a concave surface in the mathematically strict sense. Specifically, the concave surface 114 of the electrocardiograph 100 is made up of three sections, namely a main support 111 and two lateral supports 112 and 113, each lateral support being at a fixed angle α, β relative to the main support 111.
It is not easy for a patient using such a device to position the precordial electrodes on the chest, particularly while suffering an attack. In particular, the electrocardiograph 100 does not enable “perfect” contact to be guaranteed between the precordial electrodes and the precordial points of the patient's chest, in order to capture the electrocardiogram correctly. Unfortunately, the quality of the recorded electrocardiogram depends to a very large extent on the conditions with which the electrodes are applied to the patient's body, and in particular the precordial electrodes that are the most sensitive to poor positioning. In the event of poor positioning, and in particular poor contact between the electrodes and the corresponding precordial points, the electrical signals acquired by the electrodes may be greatly disturbed and unsuitable for enabling the electrocardiogram as captured in this way to be used in satisfactory manner.
This is particularly damaging when these signals of poor quality are transmitted over a telephone line in order to enable the electrocardiogram to be produced by a remote center, since the patient is not in a position to see immediately that the electrocardiogram is useless. Furthermore, the cost of the telephone call is a pure loss.
In order to minimize that difficulty, document WO 99/38436 proposes an ambulatory electrocardiograph having three precordial electrodes, with an embodiment thereof being shown in FIG. 1B. That device 120 enables an electrocardiogram to be recorded having eight leads instead of the conventional twelve.
The electrocardiograph 120 in that embodiment is provided with two arms 122 and 123, each provided with a precordial electrode (124 and 125 respectively) at its end. The third precordial electrode is situated on the bottom face 121.
The arms 122 and 123 are capable of pivoting about respective ball joints defined by axes δ and δ′ perpendicular to the bottom face 121 so as to be folded down onto the top face of the electrocardiograph 120. This enables the size of the electrocardiograph 120 to be reduced while it is not in use.
Nevertheless, it is not possible for an eight-lead electrocardiogram of the kind described in document WO 99/38436 to be analyzed by a person who has not been trained in interpreting such results, such as an emergency doctor or a general practitioner, when such a person is in the habit of interpreting twelve-lead electrocardiograms. Furthermore, the regulations presently in force in France (in particular for the Social Security services) do not recognize the use of such electrocardiographs.